Astronomers: We could find Earth-like planets soon

This image made from video provided by NASA shows an artist's rendition of what an Earth-like planet might look like. A top NASA official and other leading scientists say that within four or five years they should discover the first Earth-like planet located in a spot outside our solar system where life could develop, or may have already. (AP Photo/NASA)
— AP

This image made from video provided by NASA shows an artist's rendition of what an Earth-like planet might look like. A top NASA official and other leading scientists say that within four or five years they should discover the first Earth-like planet located in a spot outside our solar system where life could develop, or may have already. (AP Photo/NASA)
/ AP

This year, planets are being found on about a daily basis, thanks to the Kepler telescope. The number of discovered exoplanets is now well past 400. But none of those has the right components for life.

That's about to change, say the experts.

"From Kepler, we have strong indications of smaller planets in large numbers, but they aren't verified yet," said Geoff Marcy of the University of California at Berkeley. He is one of the founding fathers of the field of planet-hunting and a Kepler scientist.

But there is a big caveat. Most of the early exoplanet candidates found by Kepler are turning out to be something other than a planet, such as another star crossing the telescope's point of view, when double- and triple-checked, said top Kepler scientist Bill Borucki.

Kepler is concentrating on about one-four hundredth of the nighttime sky, scanning more than 100,000 stars, ranging from a few hundred to a few thousand light years away. A light year is about 5.9 trillion miles. So such planets are too far to travel to, and they cannot be viewed directly like the planets in our solar system.

If there were an Earth-like body in the area Kepler is searching, the telescope would find it, Marcy said. But it can take three years to confirm a planet's orbital path.

What Kepler has confirmed so far keeps pointing to the idea that there are many other Earths. Before Kepler, those bodies were too small to be seen. Borucki this week announced the finding of five new exoplanets - all discovered in just the first six weeks of planet-hunting. But all those planets were too large and in the wrong place to be like Earth.

When Kepler looked at 43,000 stars that are about the same size as our sun, it found that about two-thirds of them appeared to be as life-friendly and nonviolent as our nearest star.

Marcy, who this week announced finding a planet just four times larger than Earth, does not like to speculate how many stars have Earth-like planets. But when pressed, he said Thursday: "70 percent of all stars have rocky planets."

"If you are in the kitchen and are trying to cook up a habitable planet, we already know that in the cosmos, all the ingredients are there," he said.

While astronomers at the convention are excited about exoplanets, Marcy is more skeptical, as is Jill Tarter, director of the SETI Institute, which seeks out intelligent life by monitoring for electromagnetic transmissions. They said there is still the chance that the searches can come up empty.

Marcy said there is the small possibility that planets do not form easily at Earth's size, and that most are bigger.

Tarter - who was the basis for a character portrayed in the movie "Contact" by Jodie Foster - said: "I always worry that we talk ourselves into thinking we know more than we know."

Once an Earth-like planet is found in the right place, determining if there are the ingredients for life there will pose another hurdle.

It will require costly new telescopes. A massive space telescope to scan Earth-like planets for oxygen, water, carbon dioxide - and even faint signs of industrial emissions from civilization - would cost about $5 billion.

For now, such a high price is a budget-buster, but that could change. Cornell University astronomer Martha Haynes said: "We are at a very special moment in the history of mankind."